Process for the production of clean paper pulp from old printed paper



Patented July 18, 1933 UNITED STATES PATENT OFFICE ROBERT WEBER, OF DRENTWEDE, BEZIRK BREMEN, AND FRANZ KINNEBROCK, OF HAMELN, GERMANY;, SAID KINNEBROCK ASSIGNOR TO SAID WEBER l' PROCESS FOR THE PRODUCTION OF CLEAN PAPER PULP FROM OLD PRINTED PAPER No Drawingz. Application filed November 13, 1930, Serial No. 495,518, and in Germany November 18, 1929.

Processes are already known in which old printed paper is treated hot or cold with alkali alone or with alkalies with addition of silicates of the series of earth or alkaline earth metals, with or without protective organic colloids. The use of alkaline peroxides together with silicic acid or silicic acid compounds is also known. -It has also been proposed to subject old paper lirstto'cooking and then to. treat it with Spanish chalk (whiting), or to disintegrate it to fiber in the first stage of the' process at a tr--mperati1re of 80-120 F. and thereafter to treat the paper pulp with a mixture ofSpanish chalk and soap.

Finally, it is also known to treat. old paper with calcium hydroxide; this latter process. however, has been used. only on paper to which theprinters black has been applied by means of a mineral oil. ln this connection it is to be remarked that in practice it is not possible to sort the old papers, such as newspapers and the like, according to the kind of adhesive that has been used with the printers black. This process is therefore applicable. only Within av restricted range.

Insofar as the known processes contemplate a treatment with use of heat or even in closed container with steam under pressure they involve large extraeostsaud in some cases large losses of fibre which in most cases are economically inadmissible. In this con nection it is to be noted that the chief item in printed paper is printed newspaper, and that this ordinary paper can furnish only an ordinary, cheap recovery product. Insofar as the purpose is to free the old paper from the...

.printers black and not to transform the ground wood contained in the paper into cellulose, the ruling principle here is that for economic reasons only the cheapest solvent, the cheapest process, and the most protective treatment of the fibers in order to avoid fiber losses can come into-consideration;

Insofar as expensive solvents have to be" ing of the fibers take place.

black and dirt'ac cumulate in the partly re- .eovered solventmeans.

organic colloids are added to the alkali. -Under all circumstances, therefore, the known yellowing of the fiber will occur. The use of these substances will therefore not avoid the above mentioned disadvantages;

lt has now been found that these disadvantages can be avoided if the old paper is treated with earth alkali-containing compounds which do not act upon the old paper itself, or if it is treated with only mildly acting solvent means which have a special property for adsorbing printers black and which have a white coloring power and/or a colloidal character.

The action of these substances on the old paper is a very mild one, so that the wood fibers present in the old paper are not transformed into chemical cellulose. The means are so cheap that it will not be necessary to recover them, and the printers black is removed in one working operation at ordinary This sludge is the almost entirely alkali-free residue from the ca'ustici ation of the soda meltresulting from burning off the Waste lye,

which, notwithstanding the usual factory practice 'and the thorough. leaching imposed b I'atlOlHllO cratin rinci les' still eontalns SOITIQSOdlUIT! hydroxide, calcium hydroxide and sodium salts, but chiefly lime salts. However, the amount of alkali prescut is so small that in no case does a yellow- The melts from straw cellulose factories contain silicates on account of the silicic acid carbonate and magnesium hydroxide. This 1 in the Hollander. stance, prepared by mixing about 'litres of these silicates is very favorable to the removalof the printers ink. The removal of this latter is, however, also assisted by the 5 presence of suspensions of other lime salts and this because of the power of adhesion and the white coloring properties of these salts. I

Magnesium hydroxide has also been found preeminentl suitable for the removal of printers ink from old paper and is very cheap to produce. It may, for example, be obtained from carnallite waste liquors which, after separating out the potassium chloride, contain principally magnesium chloride and which by the addition of alkaline lyes or even causticizing sludge yield the magnesium hydroxide. This has been found to have an especially good coefficient of separation. When making it from carnallite liquor and causticizing sludge there is added to the good separation coeiiicient another phenomenon which is-to be ascribed to the presence of magnesium and lime salts and particularly to the presence of mixturesof magnesium mixture has quite extraordinary white coloring properties. v The action of causticizing sludge or mags nesium hydroxide is further materially increased by adding to these solvents suspensions of such alkaline earth salts as are of a colloidal nature and /or which possess white coloring properties. As salts of a colloidal nature, calcium and magnesium silicates, in particular, may be mentioned and as'white color carriers,in particular, barium sulphate, barium carbonate and simple and basic magnesium carbonate. Practical experiments have shown that such suspensions alone (without causticizing sludge or magnesium hydroxide) or whensuitably mixed'together are capable of loosening and removing the printers ink.

It is obvious that it is also -within the scope of this invention to produce the solvents covered by the claims from their components by mixture or by chemical decomposition.

, Example In a loosening Hollander of the well known type of construction a quantity of old printed paper is softened and disintegrated. Durmg disintegration or after it has been com.-

pleted the solvent is added and is mixed inti-= mately with the pulp by circulating the pulp The solvent is, for in carnallite waste liquor with about 120 litres of causticizing sludge for every 1000 kilograms of old pa r. To this mixture are added about 15 ki ograms of magnesiumcarbonate. The concentration of the solvent depends, obviously, on the nature of the paper 5 and of the printed matter to be removed.

1. A process for the production of a pure paper pulp from old printed paper, to which the printers black has been applied by means of any kind of adhesive, characterized by treating the old printed paper at ordinary temperature in one-single operation without any further additions with a dissolving agent which contains practically only alkaline earth compounds with the understanding that in case the hydroxides of the alkaline earth metals are used, the latter have to be of colloidal nature. v

'2. A process for the production of a pure paper pulp from old printed paper, to which the printers' black has been applied by any kind of adhesive, which comprises treating the old printed paper at ordinary temperature in 'one single operation without any further additions with a dissolving agent which contains practically only alkaline earth compounds selected from a group consiting of colloidal hydroxides of alkaline earthmetals, and compounds of alkaline earth metals other than the hydroxides.

3. A process for the production of a pure paper pulp from old printed paper, characterized by treating the old printed paper at ordinary temperature in one single operation with a dissolving agent which contains only alkaline earths dissolved colloidally, without the addition of other substances.

4. A process for the production of a pure paper pulp from old printed paper, characterized by treating the old printed paper at ordinary temperature in one single operatron with a dissolving agent containing only a suspension of alkaline earths possessing white coloring power, without the addition of other substances.

5. A process 'for the production of a pure paper-pulp from old printed paper, characterized by treating-the old printed paper at ordinary temperature in one single operation with a dissolving agent containing alkaline earths colloidally dissolved, mixed with a suspension of alkaline earths possessing white coloring power.

6. For the production of a clean paper pulp from old printed paper a method, wherein the old printed paper is treated with a causticizing sludge obtained as herein described. 7. For the production of a clean paper pul from old printed paper a method, wherein t e old printed paper is treated with magnesium hydroxide obtained fromcarnallite wasttggiquors and alkaline lycs as herein descrl a pulp from 01 8. For the production of a clean paper pulp from old printed paper a method, wherein the old printed aper is treated with magnesium hydroxide o tained from carnal alkaline earths, and causticizing sludge.

10."For the production" of a clean'paper pulp from old printed paper a method, wherein the old printed paper is treated at ordinary temperature in one single operation with a mixture containing alkaline earths, and magnesium'hydroxide obtained from carnallite waste liquors and causticizing sludge.

11. For the roduction of a clean paper d printed paper a method, wherein the old printed paper is treated at ordinary temperature in one single operation with a mixture of a suspension containing alkaline earths, and-magnesium hydroxide obtained from carnallite waste liquors and alkaline lyesv 12. For the (production'of a clean paper pulp from 01 printed paper a method, wherein the old printed paper is treated at ordinary temperature in one single operation with a mixture of a suspension 0 colloidal nature containing alkaline earths, and causticizing sludge.

13. For the production of a clean paper.

pulp from old printed paper a method,

wherein the old printed paper is treated at ordinary temperature in one single operation with a mixtu-re of alkaline earth silicates and causticizing sludge. I

14. For the (production of a clean paper pulp from 01 printed paper a method, wherein the printed old paper is treated at ordinary temperature in one single operation with a mixtureot'an aqueous suspension of calcium" silicate and causticizing sludge.

. 15. For'the production of a clean paper ulpfrom 01 printed paper a method,

wherein the old printed paper is treated at pulp from 01 ordinary temperature in one single operation with a mixture of white coloring power cpngaining alkaline'earth, and causticizing s u e.

16% For the; roduction of a clean paper printed paper a method, wherein the old printed paper is treated at ordinary temperature in one single operation with a mixture of. a suspension of white coloring power containing alkaline earths, and magnesium hydroxide obtained from ,carnallite waste liquors and causticizin sludge,

17. For the roduction of a c ean paper pulp from 01 wherein the old printed paper is treated at ordinary temperature in one single operation with a mlxture of a suspension of white coloring power containin alkaline earths,

and magnesium hydroxide obtained fromcarnallite wasteliquors and alkaline lyes. 4

18. For the roduction of a clean paper pulp from ol printed paper a method, wherein the old printed paper is treated at ordinary temperature in one single operation carbonates with a mixture of alkaline eart and causticizing sludge. a 19. For the roduction of a clean paper pulp from 01 wherein the oldprinted paper is treated. at ordinary temperature in one single operation with a mixture of magnesium carbonate and causticizing sludge.

20. For the production of clean paper pulp from old printed paper a method, wherein the old printed paper is treated with one or-more compounds selected from the group consisting of silicates, carbonates and sulphates of the alkaline earth metals.

21. For the production of clean paper pulp from old "printed paper, a method wherein the old printed paper is treated with one or more compounds selected from the group consisting ofsilicates, carbonates and sul hates of the alkaline earth metals mixed with one or more materials selected from the printed paper a method,

printed paper a method,

groupconsisting'of causticizing sludge and magnesium 

